Englishdeepen
verb
1 the recession continues to deepen | his love for his wife had been deepened by the way she had stood by him:
grow, increase, intensify, strengthen, escalate, mushroom, snowball;
add to, heighten, reinforce, enhance, boost, magnify, amplify, augment, enrich, promote, encourage;
exacerbate, aggravate, inflame, worsen, make/become worse;
informal hot up, step up.
deepen Oxford Dictionary of English