Sonnet 138

And age in love, loves not to have years told:
This means...

• DOn't tell how old you really are
• Older people do not like to talk of their age

Therefore, I lie with her, and she with me,
And in our faults by lies we flattered be.
The means...

• I deceive her, and she deceives me.  We sleep together. Even though we have imperfections we console each other.
• Therefore, we lie to each other.  Then we make love and forget about it.
• We deceive each other and then make fun of each other about it.
• We deceive each other and this makes us happy.

That she might think me some untutored youth,
Unlearned in the world's false subtleties.
Thus vainly thinking that she thinks me young,
In this passage the word, Untutored youth means

• without a tutor
• immature
• uneducated
• without knowledge

Thus vainly thinking that she thinks me young,
Although she knows that my days are past the best,
Thus is the same as saying:

• therefore
• that
• this
• thankfully

Thus vainly thinking that she thinks me young,
Although she knows that my days are past the best,
vainly means:

• to have an excessively high opinion of one's appearances, abilities or worth.
• to have many veins appear on  the body
• to not give much thought
• to overly think about others

Thus vainly thinking that she thinks me young,
Although she knows that my days are past the best,
The phrase in red means:

• To satisfy my vanity she says I am young
• She thinks I am young
• She thinks I am handsome
• She thinks she is prettier than me

Seeming trust is the same as an appearance of trusting another when in reality there is no trust, only an appearance of trust.

• true
• false

The world's false subtleties refers to:

• the cynical tactics which older people use to advance themselves
• subtle lies people tell

A false-speaking tongue is:

• someone that tells lies
• someone that uses the word false often
• a person that cannot speak
• a Ventriloquist